Abstract

Aims: The present study was planned to evaluate cytotoxic and apoptotic properties of the bark of two common mango varieties (Mangifera indica L.) grown in Sri Lanka [Rata Amba (RA) and Karthakolomban (KA)] in MCF-7 (ER positive breast cancer), MDA-MB-231 (triple negative breast cancer), SKOV-3 (ovarian epithelial cancer) cancer cell lines and normal mammary epithelial cells (MCF-10A).

Place and Duration of the Study: At the Institute of Biochemistry, Molecular Biology and Biotechnology, University of Colombo between 1^st of February 2015 to April 2015.

Methodology: Cancer cells and normal cells were treated with organic extracts (hexane, chloroform, ethyl acetate and methanol) of RA and KA bark and cytotoxic effects were evaluated by SRB assay. Free radical scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) was also tested for active extracts. Furthermore, apoptotic effects of cytotoxic extracts were analysed by caspase 3 and 7 activation, DNA fragmentation, acridine orange/ethidium bromide (AO/EB) and Hoechst staining.

Results: Of the four solvent extracts used, only the methanol extract showed anti-proliferative effects against all three cancer cell lines in a dose-dependent manner. Cytotoxicity of the methanol extract of RA was higher (MCF-7 IC₅₀– 81.1 µg/mL, MDA-MB-231 IC₅₀– 91. 5 µg/mL and SKOV-3 IC₅₀– 71.5 µg/mL) compared to that of the methanol extract of KA (MCF-7 IC₅₀– 123.9 µg/mL, MDA-MB-231 IC₅₀– 111.2 µg/mL and SKOV-3 IC₅₀– 137.2 µg/mL). Both the methanol extracts showed less cytotoxicity to normal mammary epithelial cells [IC₅₀– 255.6 µg/mL (RA) and IC₅₀– 615.6 µg/mL (KA)]. Methanol extracts also exhibited strong free radical scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH). Furthermore, methanol extract showed apoptotic effect against all tested cancer cell lines.

Conclusion: Overall findings of this study suggest that methanol extracts of the bark of two common mango varieties tested exhibit cytotoxicity through induction of apoptosis through caspase dependent mechanisms.